Closed-circuit surveillance equipment is well established and can include fixed-position cameras and zoom lenses mounted on pan and tilt mechanisms which are typically controlled by security personnel. In outdoor locations, an enclosure for the camera housing is usually employed and domed housing for such cameras are desirable due to their appearance as well as the fact that the camera itself is not easily visible, though the camera can scan a wide area.
In a typical outdoor camera enclosure, a single main housing part is utilized, wherein a top thereof is connected to a pipe. Electrical connections are generally routed from a main power source through the pipe and into the housing. In addition, a hemispheric dome and additional internal components, such as the camera power supply, camera body, lens, pan & tilt mechanism, and controller electronics, are removably attached to an inside of the single housing part. Such camera assemblies are subject to damage and require means to protect the camera from moisture and precipitation, extremes in temperature, and unauthorized tampering. For example, some conventional housings permit rain water or other moisture to accumulate and run down the conical side of the housing and onto the dome itself. Another concern is with the heat caused by sunlight or generated in the housing during use of the camera and the need to deflect such heat energy and/or to dissipate the same from the camera housing to prevent damage thereto.
Prior attempts to address some of these problems include U.S. Pat. No. 4,320,949 which, for example, in one embodiment provides a housing with a cover with a skirt over which rainwater may flow, form pendant drops, and fall, and a camera mount adapted to carry a camera and a camera positioning motor. A dome unidirectionally transparent to light is secured to the cover. The cover and dome form an air space between them. A fan is disposed in a side wall of the upper support housing to provide forced cool air circulation in the housing to cool the housing when the temperature reaches a certain predetermined level. The assembly also includes heaters which are operated when the temperature in the housing approaches freezing. In a second embodiment, air is brought into the assembly by natural circulation, i.e. a space or inlet area is provided at the interface of the support housing and cover member so that air can naturally enter the support housing about the circumference of the housing. This air is circulated downwardly adjacent the inner wall of the cover member and then up into the support housing where it is exhausted through an air exhaust port.
In U.S. Pat. No. 5,689,304, commonly assigned herewith, there is disclosed a surveillance housing assembly which comprises an outer shell having a top wall portion and side wall portion, wherein the side wall portion extends in a downward direction from the top wall portion to thereby define a first cavity. An inner shell comprises a top wall portion for mounting engagement with an underside of the top wall portion of the outer shell within the first cavity. The inner shell further comprises a top wall portion and a side wall portion, wherein the side wall portion extends in a downward direction from the top wall portion to thereby define a second cavity. The top wall portion 18 of the outer shell 12 has an exhaust aperture 32 positioned off-center from a central axis 34 of the outer shell; a generally circular aperture 36 is centered on the central axis and is provided in the top wall portion 18 to enable cable to pass through; and the top wall portion 22 of the inner shell 14 has an air exhaust aperture designed to be coincident with the air exhaust aperture 32 of the top wall portion 18 of the outer shell 12; and still further, the top wall portion 22 of the inner shell 14 has a generally circular aperture which is coincident with the aperture 36. Air inlet apertures 44 define an air flow to exhaust 32. The housing also has a decorative cap 70 which has a plurality of notches along its bottom edge which, cooperate with other parts to provide a path for an exhaust air flow and provides for protection against an ingress of unwanted water. This assembly also comprises various combinations of heaters and blowers. Further in this arrangement, a sequence of wall surfaces and plateau surfaces are arranged for securing components of the surveillance equipment thereto in a prescribed manner such that first components of the surveillance equipment are disposed in between the underside of the outer shell and an outerside of the inner shell, and second components of the surveillance equipment are disposed within the second cavity.
While air circulation via fans and exhaust ports and/or airintake valves and air-exhaust valves is satisfactory to compensate for environmental temperature changes in some surveillance systems, it has its limitations, most notably in terms of added cost and complexity, size and power constraints occasioned by the need to incorporate such components into the surveillance assembly.
There remains a need in the art for a camera surveillance system which does not suffer from the disadvantages set forth above and which provides protection to the camera from moisture and heat without imposing undesirable size and power constraints.